Cellular adhesion and migration mechanisms have been recognized as crucial elements regulating the fate and function of most transfused blood cells. As such, the direct visualization of cell adhesion properties and the fine structural feature that influence these properties is central to our understanding of how transfused cells participate in inflammation, hemostasis, thrombosis and immunity. The Imaging Core has been formulated based on a stated need of PPG investigators and is designed to draw on the considerable experience of its co-directors to provide advice, expertise and specialized equipment in the design and execution of cutting-edge imaging studies on the role of cell adhesion molecules in transfusion biology. The Specific Aims of the Imaging Core are as follows: 1. To provide instruction, equipment and assistance in the execution and analysis of intravital microscopybased adhesion and migration studies in murine tissues. Currently available models include: cremaster muscle;ear skin;bone marrow;liver;popliteal and inguinal lymph node;bladder;knee joint;and small intestine, including mesentery, Peyer's patches and lamina propria. 2. To provide instruction, equipment and assistance for scanning and transmission electron microscopy studies, including specialized sample preparation, immunogold labeling, high resolution imaging, and data interpretation. 3. To provide access to and expertise in multi-photon microscopy-based recording of intra- and extravascular blood cell adhesion, migration and cell-cell interactions in as many as six dimensions (i.e. space, time, color, fluorescence intensity). 4. To provide instruction and assistance in the planning, execution and analysis of blood cell homing in vivo employing defined models of inflammation. Services to be provided by the Imaging Core will allow participating investigators to explore how defined adhesion pathways influence blood cells interactions with their environment at a resolution ranging from single molecules to intact animals.